Simple 25 independant LED control using only 10 switches/IO's, Usefull in arduino projects where you don't want to use shift reg's etc but want to use least amount of IO, So an UNO can run these with IO to spare, Limitation is that you can only light up squares anywhere in the matrix or vertical/horizontal lines, no diagonals unless of course you multiplex in which case you can do ANY shape/line etc the matrix resolution allows.
